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Topic: SE adjustable pushrods!!! (Read 10943 times)

So I have been reading about the adjustable pushrods. They they are 32 threads per inch. I read that the twin cam lifter has about .200" of travel. The HD instructions say to adjust the pushrod from zero lash into the lifter 2.5 turns. Most threads I have read say that will put the lifter at .100 compressed. So hear is my question? At 32 threads per inch that gives one turn on the pushrod at .03125 and multiply that by 2.5 and you are at .078" not .100". Along with that I have read on several forums that some people in the industry recommend putting the lifter .140-.150 " compressed. I read all the Black hills ken thread and its pretty interesting. Anyone want to weigh in on the .078" number as well as why a couple of the top guys recommend .140-.150" into the lifter which should be 4.48 turns -4.8 turns ?

I have tried the 2.5/1.5,1 turn . The one turn gives me some lifter noise at start up should the bike sit for a week or so. I have two bikes so sometimes one gets more action.

i could be wrong, but i think the old S/e's are 32 tpi and the new tapered ones are 24 tpi....i could be wrong though.

I need to edit that actually. The "SE" reference there is old enough that it is now the "old" SE pushrods. I don't know what the thread count on the new tapered pushrods is. Will edit that prior post accordingly. Thanks for the reminder. Anyone know for sure on the new SE tapereds?

i could be wrong, but i think the old S/e's are 32 tpi and the new tapered ones are 24 tpi....i could be wrong though.

I need to edit that actually. The "SE" reference there is old enough that it is now the "old" SE pushrods. I don't know what the thread count on the new tapered pushrods is. Will edit that prior post accordingly. Thanks for the reminder. Anyone know for sure on the new SE tapereds?

it's easy to see, 32 TPI is finer than 24 TPI, just count the threads in 1/2" and multiply by 2, what is the answer ?

Mine are the regular screaming eagle pushrods not the new tapered? Pretty much everything I have read is saying they are 32tpi. I am about to readjust mine and I have a thread pitch gauge so I am going to make certain what they are but all I read is that they are 32 tpi. I agree on the 3.5 turns calculation. Thats what I got also. Anyone on the .140-.150 preload?

I am not claiming to be a top guy, but I will answer the question. Milling the gasket surface in an attempt to reduce combustion chamber size, using thinner gaskets, sinking the valves deeper, etc... changes, (increases) the angle between the rocker and lifter, these changes how ever slight add stress to the valve train and do have an effect, driving the contact point of the lifter deeper into the hole can correct some of these changes, and the change can be noticed. Just like any of this stuff, YMMV.

Additional preload can sometimes help to reduce valve train noise as well as help with hot starts. The additional preload makes the lifter look more like a limited travel lifter and thus will alter the valve timing less due to bleed down. There is a potential downside to both too much and too little preload ... but I've found that most just don't want to hear it so ... me lips be sealed :>) In a perfect world, the plunger should be set to the mid travel point as this will allow the lifter to maintain zero lash over the largest possible range of operation ... BWTFDIK! :>)

Too much preload ... If valve float should occur, the lifter can pump up and possible valve to piston contact is possible. Less than optimum pushrod to lifter angle is also a consideration.

Too little preload: Potential for the lifter to not be able to maintain zero lash. This can have more effects than just valve train noise. In addition to a less than optimum pushrod to lifter angle it is also possible for the lifter plunger retainer to fail as it is not designed to retain the plunger under operating loads.

I have seen both of the above occur, it usually ain't pretty when it happens. There's more, but the above are the major concerns.

Ed, I want to hear it and I know others do too. Let's hear the upsides and downsides to both senerios. thanks jeff

The new screamin eagle tapered pushrods are 24 tpi. I used them with S&S limited travel lifters (.100 total plunger travel). I probably set the pushrod length ass-backwards as compared to some, but I extend the pushrods until the pushrod plunger is completely depressed (the lifter plunger has traveled .100), then I back up (shorten) the pushrod length just a tad over 1 full turn (shorten the pushrod just over .0416) - so I am approx. in the middle of the plunger travel. (for the unfamiliar, a "tad" is a technical term...)

>>Does any body still do that or was that just another one of those TTOTM?<<

Dunno, if they are they ain't sayin'. Same stuff goes on with the GM, Ford, etc. performance forums. Ford itself was promoting the light preload on 5 liter Mustangs for awhile, then backed off when some managed to separate the plungers from the lifter bodies at 7000 RPM ... nasty! We HD'rs have some additional considerations ... aluminum and air cooled strike a chord with anyone?